Should I change speaker cables?

I am currently using Harmonic Tech Pro9+ but at time I feel the sound may be a little on the warm side and makes things congested with bass heavy materials. Although I don't know if it's my sytem or the cables but I am think of buying a pair of Nordost Blue Heaven to try out.

System consists of Living Voice Avatar, VTL Deluxe Mono 120, Musical Fidelity Pre24 and HT Pro Silway II.
Pro 9+ are fine cables. I found, however, that the skinny little Audience AU-24 cables outperformed them in every aspect. You may want to try these and see how they work for you.
Don't buy anything. Call The Cable Co. and get a loaner from almost any brand you can name and try them out for a week. It's the only way to go. Call 1-800-Fatwyre. I do not represent them, but have dealt with them for years.
I second Elinor's recommendation, but would add that their advice as to which cables to use has been outstanding too!
Try anything that Transparent makes and you'll be happy you did. Their cables are amazing.
Another option. You can also try the Ah! Direkt Cables. They are supposedly swiss made but look quite humble. However, I was stunned at how good they sound compared to cables 3 times their prices. They sound vivid (present), open (extended at both extremes), airy and fast. Music just flows...